This invention relates to a method of regulating the flow of molten metal through the pouring opening of a vessel.
Conventionally, the performance of a device for regulating the flow of liquid such as a device for regulating the flow of molten metal through a pour opening of a vessel is not satisfactory particularly when a fine or delicate adjustment, e.g., from 1 to several mm, is required. This is especially true when a stopper, as shown in FIG. 5, is employed as the device for regulating the flow of molten metal through the pour opening of a vessel into a continuous casting machine to produce various kinds of slabs or the like.
This conventional regulating method has a serious fault; namely, fine regulation of the flow of molten metal through the pour opening of the vessel is impossible.
Furthermore, since the stopper head is always subjected to a force which tends to pull the head down into the pour opening, the head is often fractured.
In order to solve the above problem, a sliding nozzle which is shown in FIG. 6 has recently been developed and which is principally used as the device to regulate the flow of molten metal from a vessel. The sliding nozzle has achieved great success in preventing accidents which have arisen with the stopper means.
However, a problem still exists with the above regulating method. That is, this method which utilizes the sliding nozzle usually comprises two or three plates wherein one of them is moved in order to regulate the relative size of the opening of each plate; thereby the flow of the molten metal flowing through the pour opening is determined by the size of the opening or the amount that the plate has been slid. Usually a method to regulate the above sliding distance of the plate is conducted by regulating the amount of oil supplied to a hydraulic cylinder which causes the sliding movement of the plate. However fine regulation of the sliding length of the plate per single actuation of the cylinder is difficult to obtain.
Accordingly, even a skilled operator cannot regulate the sliding distance of the plate 1 mm to several mm but greatly exceeds the desired sliding distance which is necessary to produce small-sized slabs such as blooms of good quality. Even when the operator manages to successfully finely adjust the distance, he must conduct frequent open-and-close sliding operations to obtain stability of the surface of the molten metal in the mold which requires the operator's delicate and utmost care. Furthermore, the above frequent sliding operations cause rapid corrosion of the plates and thereby results in turbulence in the flow of molten metal through the pour opening of the vessel.
It is an object of the present invention to provide a method for finely regulating the flow of molten metal in such a way that the plate of the sliding nozzle is slid precisely bit-by-bit within a small stroke in a short period, while eliminating the disadvantages of the methods and apparatuses fo the prior art.
It is an object of the present invention to provide an apparatus for finely regulating the flow of molten metal through a pour opening of a vessel which is simple in construction and yet is capable of achieving the fine adjustment of the operation of the sliding nozzle.
It is a further object of the present invention to provide a method as well as an apparatus for finely adjusting the flow of molten metal glass through the pour opening of a vessel.
Due to the method and apparatus of this invention, the sliding distance of the plate of the sliding nozzle can be precisely regulated at the minimum to a length of 0.2mm so that the desired sliding distance necessary to produce blooms or slabs of good quality can be easily obtained. Furthermore, if this device is coupled with a device for detecting the level of molten metal in the mold, automatic pouring of the molten metal can be achieved.